1. Field of the Invention
The present invention relates to a refrigerant compressor and, more particularly, to a valved discharge mechanism of a refrigerant compressor used in an automotive air conditioning system.
2. Description of the Prior Art
Valved discharged mechanisms of refrigerant compressors are well known in the prior art. For example, FIG. 7 depicts a valved discharge mechanism used in the refrigerant compressor described in U.S. Pat. No. 4,978,285. As disclosed therein, a refrigerant compressor includes a compressor housing defining a compression chamber in which successive strokes of intake, compressing, and discharge of a refrigerant gas are repeatedly performed. Further, the compressor includes valve plate 65 which is formed to partition the compression chamber from a discharge chamber and a discharge valve assembly mounted on an end surface of valve plate 65. Valve plate 65 has discharge hole 652 extending therethrough and allowing communication of the compression chamber with the discharge chamber. The discharge valve assembly includes discharge reed valve 81 and valve retainer 80 which are secured together to outer surface 65a of valve plate 65 by fixing bolt 82. Discharge reed valve 81, which is made of elastic material, regulates the flow of the refrigerant gas and makes sealing contact against end surface 65a of valve plate 65 without air gap when the operation of compressor is stopped.
Valve retainer 80 limits the bending movement of discharge reed valve 81 in the direction in which the refrigerant gas leaves the compression chamber and enters the discharge chamber through discharge hole 652. Discharge reed valve 81 bends to close and open one end opening of discharge hole 652, and has a predetermined value of elastic modulus which allows discharge reed valve 81 to keep one end opening of discharge hole 652 closed, until a pressure in the compression chamber reaches a predetermined value.
In such arrangement, discharge reed valve 81 strikes retainer 80 when it opens. On the other hand, discharge reed valve 81 strikes end surface 65a of valve plate 65 when it closes. Thus, a compressor with such a discharge valve arrangement disadvantageously generates vibration and noise during operation due to this striking. Particularly, vibration and noise caused by reed valve 81 striking end surface 65a of valve plate 65 is disadvantageous. After refrigerant is discharged, reed discharge valve 81 returns to its closed position due to elastic restoring force. The magnitude of the elastic restoring force is sufficiently large to cause discharge reed valve 81 to bend past the plane of end surface 65a before returning to its closed position (for instance, valve 81, if unobstructed, may return to its closed position through a damped periodic motion). End surface 65a, however, presents an obstacle to discharge reed valve 81. Therefore, the elastic restoring force causes reed valve 81 to strike end surface 65a of plate 65 and thereby generate a large amount of noise and vibration. This offensive noise and vibration propagates to the passenger compartment of the vehicle.